Magnetic resonance imaging device

ABSTRACT

An MRI apparatus having a configuration that reduces vibration of a static magnetic field generating source is provided. A closed vessel  2  of the static magnetic field generating source is provided with a rigid structure  4  for preventing transmission of vibration generated from a gradient magnetic field generating part  21  to other members via the closed vessel  2 . The rigid structure  4  uses, for example, a connecting part  4  that connects a face  25  on the imaging space side and a face  26  confronting it. The rigidity of the closed vessel is thereby increased, and therefore vibration transmitted from the gradient magnetic field generating part can be reduced. The connecting part can have a through-hole structure, and in such a case, internal space of through-hole can be used for drawing cables.

TECHNICAL FIELD

The present invention relates to a magnetic resonance imaging apparatus(henceforth referred to as “MRI apparatus”).

BACKGROUND ART

MRI apparatuses include those of a type using one pair of opposinglydisposed static magnetic field generating sources, in which a uniformstatic magnetic field region is formed in the space between the pair ofstatic magnetic field generating sources. An imaging portion of asubject is disposed in this uniform static magnetic field region andimaged. An MRI apparatus using opposingly disposed static magnetic fieldgenerating sources has advantages that it can give open feeling to asubject, and the subject is more easily accessed by an operator comparedwith an MRI apparatus of a type using a cylindrical static magneticfield generating source. As the static magnetic field generating source,a permanent magnet, resistive type magnet or superconducting magnet isgenerally used.

A gradient magnetic field generating coil and a high frequency magneticfield generating coil are disposed on the surface on the imaging regionside of each of the pair of static magnetic field generating sources.Because a pulse current flows in the gradient magnetic field generatingcoil in accordance with an imaging pulse sequence, it generatesvibration due to the Lorentz force. Therefore, there is a problem thatthis vibration is transmitted from the body of the gradient magneticfield generating coil via cables thereof to the static magnetic fieldgenerating source, and thus the static magnetic field generating sourcevibrates.

Japanese Patent Unexamined Publication (KOKAI) No. 2002-52004 disclosesa structure in which a gradient magnetic field coil is supported by asupporting system disposed through a hole provided at the center of astatic magnetic field generating source. This supporting system is notin contact with the static magnetic field generating source, and ismechanically separated form a supporting system of the static magneticfield generating source. Transmission of vibration generated by thegradient magnetic field generating coil to the static magnetic fieldgenerating source is thereby suppressed.

However, in the configuration described in Japanese Patent UnexaminedPublication (KOKAI) No. 2002-52004 mentioned above, the gradientmagnetic field coil is supported by the supporting system at the centralpart thereof, and therefore the gradient magnetic field coil is likelyto deform and also generate vibration. For this reason, it becomesdifficult to improve the performances of the gradient magnetic fieldcoil (for example, linearity of the gradient magnetic field, lowvibration property of the gradient magnetic field coil etc.). Moreover,vibration is generated also in cables connected in order to supply acurrent to the gradient magnetic field coil, and reduction of thisvibration is not taken into consideration. Furthermore, how to drawcables for supplying a current to the gradient magnetic field coil andpiping for circulating cooling water to the outside is not taken intoconsideration, either.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide an MRI apparatus havinga configuration that reduces vibration of a gradient magnetic field coiland cables.

To achieve the aforementioned object, in the MRI apparatus according tothe first embodiment of the present invention, a static magnetic fieldgenerating source comprises a magnetic field generating-coil and aclosed vessel enclosing the magnetic field generating coil inside, andthe closed vessel has a rigid structure in order to prevent transmissionof vibration generated by a gradient magnetic field generating part toother members via the closed vessel. The gradient magnetic fieldgenerating part is supported on a face of the closed vessel on theimaging space side. Because the closed vessel has a rigid structure, itbecomes unlikely to vibrate, thereby vibration generated in the closedvessel by vibration of the gradient magnetic field generating part canbe suppressed, and vibration of the gradient magnetic field generatingpart fixed on such a closed vessel can be suppressed. Furthermore,because vibration of the closed vessel itself is suppressed,transmission of vibration from the gradient magnetic field generatingpart to other members via the closed vessel can be prevented.

The aforementioned rigid structure can comprise at least one connectorwhich connects a face on the imaging space side and an opposite face ofthe closed vessel inside the closed vessel. By connecting theconfronting faces of the closed vessel as described above, the rigidityof the closed vessel can be improved.

The aforementioned rigid structure can further comprise a rigidreinforcing member fixed on a face confronting the face on the imagingspace side of the closed vessel. The rigidity of the face of the closedvessel confronting the face on the imaging space side is therebyimproved, and the rigidity of the face on the imaging space side is alsoindirectly improved via a connecting part. As a result, the rigidity ofthe closed vessel as a whole can be improved without using a largerthickness for the face on the imaging space side, and at the same time,it becomes possible to secure a large imaging volume.

The aforementioned rigid reinforcing member can comprise at least one ofa plate member and a grid member. When a grid member is used as therigid reinforcing member, the rigidity can be enhanced with a smallerweight of the closed vessel. That is, by using a grid member, weightincrease of the closed vessel due to use of the rigid reinforcing membercan be reduced.

The aforementioned plate member can be integrally formed with the closedvessel by thickening a wall of the face confronting the face on theimaging space side of the closed vessel compared with the wall thicknessof the face on the imaging space side. The rigidity of the closed vesselcan be thereby further enhanced.

The aforementioned gradient magnetic field generating part can beintegrated with the closed vessel by fixing the part to the closedvessel with a fixing means. Integration of the gradient magnetic fieldgenerating part with the closed vessel that has an enhanced rigidity bythe rigid structure and thus is unlikely to vibrate enables suppressionof vibration of the gradient magnetic field generating part.

Each closed vessel mentioned above can have a first recess formed on theface on the imaging space side. In this case, each gradient magneticfield generating part is fixed in the first recess. The connecting partincludes one or more through-holes penetrating from the face on theimaging space side to the confronting face in the inside thereof. In atleast one of the through-holes, cables for gradient magnetic field forsupplying a current to the gradient magnetic field generating part canbe disposed. By disposing the gradient magnetic field generating part inthe first recess as described above, a large region of the imaging spacecan be secured. By using the through-holes as the connecting part of theclosed vessel and disposing cables for gradient magnetic field therein,it becomes unnecessary to lay cables for gradient magnetic field on theimaging space side, thus a large imaging volume can be secured, and thephenomenon that vibration of the cables transmits to the closed vesselcan be ameliorated.

The aforementioned closed vessel can have a second recess in the faceconfronting the face on the imaging space side, and the rigidreinforcing member can be disposed inside the second recess. The weightof the closed vessel can be thereby reduced. That is, increase of theweight of the closed vessel due to use of the rigid reinforcing membercan be reduced by providing the second recess.

As for arrangement of the aforementioned through-holes, they can beprovided adjacent to the side of the first recess.

As for arrangement of the aforementioned through-holes, at least one ofthe through-holes can be provided at an approximate center of the firstrecess.

The aforementioned rigid reinforcing member can have pathwayscommunicating with the through-holes inside, and cables for gradientmagnetic field can be disposed in one of the pathways.

In the aforementioned MRI apparatus, a means for circulating arefrigerant for cooling the gradient magnetic field generating part canbe further disposed. In such a case, the gradient magnetic fieldgenerating part can be provided with a means for passing the refrigerantinside. In this case, piping for supplying the refrigerant to thegradient magnetic field generating part may be disposed in at least oneof the through-holes and a pathway communicating therewith.

In the aforementioned MRI apparatus, a pair of high frequency magneticfield generating parts for generating a high frequency magnetic field inthe imaging space can be further disposed. Each of the pair of highfrequency magnetic field generating parts is disposed on the imagingspace side with respect to the gradient magnetic field generating part.In at least one of the through-holes and a pathway communicatingtherewith, cables for high frequency magnetic field for supplying acurrent to the high frequency magnetic field generating part can bedisposed.

It is possible to provide three or more through-holes in theaforementioned closed vessel, and the cables for gradient magneticfield, cables for high frequency magnetic field and piping can bedisposed individually in either of separate through-holes and in eitherof separate pathways. The aforementioned pathways can join inside therigid reinforcing member and communicate with the outside of the rigidreinforcing member as pathways of a smaller number than the number ofthe through-holes. In the joined pathways, there can be provided apartition that separates a space through which the cables for gradientmagnetic field or the cables for high frequency magnetic field run and aspace through which the piping runs, and the partition may beconstituted with a material of high thermal conductivity. Theaforementioned piping can be disposed at a position perpendicularlyunder the cables for gradient magnetic field or the cables for highfrequency magnetic field.

The aforementioned through-hole can have an opening inside the firstrecess, the gradient magnetic field generating part can have a currentreceiving terminal at a position of the opening of the through-hole, andthe cables for gradient magnetic field can have a current supplyingterminal, wherein the current supplying terminal is connected to thecurrent receiving terminal.

The aforementioned cables for gradient magnetic field can be fixed inthe through-hole with a fixing member. Vibration transmitted via cablesto the closed vessel can be thereby further reduced.

The aforementioned through-hole can have an opening inside the firstrecess, the gradient magnetic field generating part can be configured tohave a refrigerant receiving terminal at a position of the opening ofthe through-hole, and the piping can have a refrigerant supplyingterminal, wherein the refrigerant receiving terminal is connected to therefrigerant supplying terminal.

The aforementioned piping, refrigerant supplying terminal andrefrigerant receiving terminal can be constituted with a conductivematerial, so that they can serve also as the cables for gradientmagnetic field supplying an electric current to the gradient magneticfield generating part.

BRIEF EXPLANATION OF THE DRAWINGS

FIG. 1 is a block diagram showing overall configuration of the MRIapparatus according to the first embodiment.

FIG. 2 is a perspective view of a static magnetic field generatingapparatus 1 of the MRI apparatus according to the first embodiment.

FIG. 3 is a partial sectional view of a lower superconducting magnet 101b of the MRI apparatus according to the first embodiment.

FIG. 4 is a partial sectional view of a lower superconducting magnet 101b of the MRI apparatus according to the second embodiment.

FIG. 5( a) is a lower view of a lower superconducting magnet 101 b ofthe MRI apparatus according to the second embodiment, and FIG. 5( b) isa partial side view of a grid reinforcing member 52 of the lowersuperconducting magnet 101.

FIG. 6 is a sectional view of a lower part of the lower superconductingmagnet 101 b of the MRI apparatus according to the third embodiment.

FIG. 7 is a partial sectional view of a lower superconducting magnet 101b of the MRI apparatus according to the fourth embodiment.

FIG. 8 is a sectional view of a lower part of a lower superconductingmagnet 101 b of the MRI apparatus according to the fifth embodiment.

FIG. 9 is a sectional view of a lower part of a lower superconductingmagnet 101 b of the MRI apparatus according to the sixth embodiment.

FIG. 10 is a sectional view of a lower part of a lower superconductingmagnet 101 b of the MRI apparatus according to the sixth embodiment.

FIG. 11 is a front view of an opening 71 b of a plate reinforcing member51 of the MRI apparatus according to the sixth embodiment.

FIG. 12 is a sectional view of a static magnetic field generatingapparatus 1 of the MRI apparatus according to the seventh embodiment.

FIG. 13 is a sectional view showing a static magnetic field generatingapparatus of the magnetic resonance imaging apparatus of the eighthembodiment.

FIG. 14 is a sectional view-showing a fixation structure (fixing agenttype) of a cable according to the eighth embodiment.

FIG. 15 is a sectional view showing a fixation structure (cushioningtype) of a cable according to the eighth embodiment.

FIG. 16 is a sectional view showing a fixation structure (guide railtype) of a cable according to the eighth embodiment.

FIG. 17 is a sectional view showing a terminal connecting structureaccording to the eighth embodiment.

FIG. 18 is a top view of the terminal connecting structure according tothe eighth embodiment shown in FIG. 17.

FIG. 19 is a top view of a terminal connecting structure according tothe eighth embodiment.

FIG. 20 is a sectional view of a static magnetic field generatingapparatus of the magnetic resonance imaging apparatus according to theninth embodiment.

FIG. 21 is a sectional view showing a terminal connecting structureaccording to the ninth embodiment.

FIG. 22 is a sectional view showing a terminal connecting structureaccording to the ninth embodiment.

FIG. 23 is a sectional view showing a terminal connecting structure ofpiping according to the tenth embodiment.

FIG. 24 is a sectional view showing a connecting structure of pipingusing a lock type connector according to the tenth embodiment.

FIG. 25 is a sectional view showing a connecting structure of pipingusing a rubber tube according to the tenth embodiment.

FIG. 26 shows a connecting structure of piping using a connectoraccording to the tenth embodiment.

FIG. 27 is a sectional view showing a structure connecting piping at anapproximate center of a recess 3 according to the tenth embodiment.

FIG. 28 is a sectional view of a static magnetic field generatingapparatus according to the eleventh embodiment.

FIG. 29( a) is a sectional view of a lower superconducting magnet 101 baccording to the twelfth embodiment, and FIG. 29( b) is a sectional viewshowing a configuration in which a recess 3 and a through-hole 4 areformed in the superconducting magnet 101 b shown in FIG. 29( a).

FIG. 30 is a sectional view of a lower superconducting magnet 101 baccording to the thirteenth embodiment.

FIG. 31( a) is a sectional view of a lower superconducting magnet 101 baccording to the fourteenth embodiment, and FIG. 31( b) includes anenlarged sectional view of a part of FIG. 31( a) and a perspective viewof a nut and a screw.

FIG. 32 is a sectional view showing a structure for attaching a baseaccording to the fourteenth embodiment to fix a gradient magnetic fieldcoil with a bolt.

FIG. 33 is a perspective view showing overall configuration of the MRIapparatus according to the first embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the magnetic resonance imaging apparatus (MRI apparatus)according to the present invention will be explained with reference tothe drawings.

First Embodiment

The MRI apparatus according to the first embodiment comprises, as awhole view thereof is shown in FIGS. 1 and 33, a static magnetic fieldgenerating apparatus 1, a gradient magnetic field coil 21, a highfrequency irradiating coil 22, a bed 131 on which a subject 129 is laid,and a high frequency receiving coil 132. Besides these, the apparatusincludes a gradient magnetic field power source 135, a high frequencyapparatus 134, a control apparatus 137, an operating apparatus 128, aninput device 141 and a display 130 as control and operation systems.Moreover, as shown in FIG. 1, the apparatus also comprises a heatexchanger 4001 and a pump 4002, which supply a refrigerant such ascooling water to the gradient magnetic field coil 21.

The static magnetic field generating apparatus 1 comprises, as shown inFIGS. 2, 3 and 33, a pair of superconducting magnets 101 a and 10 b,which are opposingly disposed on the upper side and lower side, and twoof connecting columns 6 connecting them. The pair of superconductingmagnets 101 a and 101 b produce an intense and uniform static magneticfield region (imaging volume) 9 in the space between them. The directionof the magnetic field is the direction of Z. The bed 131 carries asubject 129, and an imaging portion is placed in the uniform staticmagnetic field region 9. The gradient magnetic field coil 21 and thehigh frequency irradiating coil 22 are disposed on the side of thesubject 129 (opposing face side) of the superconducting magnet 101 a or101 b as shown in FIG. 1. The high frequency irradiating coil 22irradiates a high frequency magnetic field pulse having a frequencyequal to the Larmor frequency on the imaging portion. Nuclear spins arethereby excited in the subject 129 and emit NMR signals. A receivingcoil 132 disposed near the imaging portion detects the emitted NMRsignals. The gradient magnetic field coil 21 applies gradient magneticfields to the uniform static magnetic field region 9 for threedirections of X, Y and Z axes in order to add positional information tothe NMR signals.

The NMR signals received by the receiving coil 132 are detected by thehigh frequency apparatus 134 and transmitted to the operating apparatus128 to perform an image reconstruction operation and so forth. Thereconstructed image is outputted to the display 130 and displayed.Further, in addition to the detection of the signals received by thereceiving coil 132, the high frequency apparatus 134 also performssupply of high frequency power to the high frequency irradiating coil 22for generating a high frequency magnetic field pulse. The gradientmagnetic field power source 135 supplies a current to the gradientmagnetic field coil 21 to generate a predetermined gradient magneticfield. The control apparatus 137 controls operations of the gradientmagnetic field power source 135 and the high frequency apparatus 134. Apredetermined imaging pulse sequence instructed by an operator via theinput device 141 is thereby executed. Further, an image desired by theoperator is reconstructed by controlling operation and processing in theoperating apparatus 128.

Hereafter, the detailed structure of the superconducting magnets 101 aand 101 b will be explained with reference to the sectional view of thesuperconducting magnet 101 b shown in FIG. 3. The superconductingmagnets 101 a and 101 b each comprise a cryostat 2 and a superconductingcoil group 11 accommodated inside the cryostat. The cryostat 2 comprisesa refrigerant container 33 filled with helium as the refrigerant and avacuum vessel 31 fixed outside the refrigerant container with apredetermined interval. The superconducting coil group 11 is allocatedinside the refrigerant container 33. The space between the refrigerantcontainer 33 and the vacuum vessel 31 is decompressed to a predetermineddegree of vacuum. Further, a thermal radiation shielding layer (notshown) is disposed in the vacuum space between the refrigerant container33 and the vacuum vessel 31 so that the layer should wrap therefrigerant container 33. By such a structure, the temperature of thesuperconducting coil group 11 is maintained at a temperature below thesuperconducting transition temperature. As the refrigerant container 33and the vacuum vessel 31, those made of stainless steel or glass fiberreinforced plastics (GFRP) can be used.

The superconducting coil group 11 has a configuration of active sealedtype for preventing leakage magnetic field and comprises thesuperconducting coil 12 which generates a magnetic field forming thestatic magnetic field region 9, the superconducting coil 13 forshielding which generates a magnetic field for preventing leakagemagnetic field and the superconducting coil 14 for correction forimproving uniformity of the static magnetic field. It is also possibleto replace the superconducting coil 13 for shielding and thesuperconducting coil 14 for correction with ferromagnetic substances.

The cryostat 2 has a cylindrical outer shape, and a recess 3 is providedin the wall of the face 25 on the side of the uniform static magneticfield region 9 (opposing face) as shown in FIGS. 2 and 3. That is, thewall 31 a of the vacuum vessel 31 constituting the opposing face 25 andthe wall 33 a of the refrigerant container 33 are depressed in the shapeof the recess 3. The gradient magnetic field coil 21 is supported by afixing part 15 disposed inside the recess 3 and fixed to the cryostat 2.As the means for fixing the gradient magnetic field coil 21 with thefixation part 15, adhesion with adhesive or the like, fastening withbolt or the like and so forth can be used. The high frequencyirradiating coil 22 is disposed in the recess 3 on the side of imagingspace 9 with respect to the gradient magnetic field coil 21. Further, ashim coil for correcting the static magnetic field can also be disposedin the recess 3 as required. By disposing the gradient magnetic fieldcoil 21, the high frequency irradiating coil 22, the shim coil and soforth in the recess 3 as described above, the gradient magnetic fieldcoil 21, the high frequency irradiating coil 22 and so forth do notprotrude into the space between the upper and lower superconductingmagnets 101 a and 101 b. The space between the upper and lowersuperconducting magnets 101 a and 101 b can be thereby made large, andtherefore open feeling can be given to the subject 129.

Further, as shown in FIG. 2, as for the cryostat 2 for each of thesuperconducting magnets 101 a and 101 b, a structure reinforcing memberis fixed on the face 26 on the side opposite to the opposing face 25(non-opposing face). In this embodiment, a thick plate reinforcingmember 51 constituted with a material having a high rigidity is used asthe structure reinforcing member. The material of the thick platereinforcing member 51 may be a material having a high rigidity, and forexample, a metal or ceramics can be used. A larger thickness of thethick plate reinforcing member 51 is more desirable, because a largerthickness provides a larger rigidity. However, a larger thicknessresults in a lager weight and also requires a larger space fordisposition. Therefore, considering these factors, the member having anappropriate thickness is used. As the method for the fixation of thethick plate reinforcing member 51, for example, a method of firmlyanchoring it to the whole or a part of the non-opposing surface 26 ofthe cryostat 2 by welding, adhesion or the like, or a method offastening it with many bolts can be used. The thick plate reinforcingmember 51 thereby reinforces the rigidity of the non-opposing face 26 ofthe cryostat 2.

Further, multiple through-holes 4 penetrating from the non-opposing face26 to the opposing face 25 are provided in the cryostat 2. The wall ofeach through-hole 4 has a dual-structure consisting of a wall 33 bextended from the refrigerant container 33 and a wall 31 b extended fromthe vacuum vessel 31 and thus maintains a heat insulated structure. Thewalls of the through-holes 4 act as columns supporting the opposing face25 on the non-opposing face 26. Because the rigidity of the non-opposingface 26 is enhanced by the thick plate reinforcing member 51, thesupport of the opposing face 25 at multiple positions by the walls ofthe through-holes 4, of which one ends are fixed to the non-opposingface 26, can enhance the rigidity of the opposing face 25 of thecryostat 2.

Because the superconducting magnets 101 a and 101 b are required toefficiently generate the static magnetic field region 9 of a strongintensity, it is desirable to make the interval between the walls 31 aand 33 a of the cryostat 2 and thickness thereof as small as possible,and thereby make the superconducting coil 12 as near the static magneticfield region 9 as possible. For this reason, it is not easy to enhancethe rigidity of the opposing face 25 of the cryostat 2. However,according to this embodiment, by disposing the thick plate reinforcingmember 51 on the side of the non-opposing face 26 to enhance therigidity thereof and providing the through-holes 4 penetrating from thenon-opposing face 26 to the opposing face 25, the rigidity of the wallof the opposing face 25 can be enhanced without increasing the thicknessthereof.

It is known that because a pulse current corresponding to an imagingpulse sequence is supplied to the gradient magnetic field coil 21 fixedin the recess 3 of the opposing face 25 from the gradient magnetic fieldpower source 135, pulsed Lorentz force is induced to generate vibration.This vibration transmits to the walls 31 a and 33 a of the cryostat 2 onwhich the gradient magnetic field coil 21 is fixed. However, because thewalls 31 b and 33 b of the through-holes 4 disposed at multiplepositions support them as columns, vibration of the walls 31 a and 33 aconstituting the opposing face 25 can be effectively reduced.

As for the number and arrangement of the through-holes 4, a number andarrangement effectively suppressing the vibration are determined bysimulation or the like considering frequency of vibration generated inthe gradient magnetic field power source 135, characteristic vibrationfrequency of the cryostat 2, weight, thickness etc. of the thick platereinforcing member 51 and so forth, and the actual number and positionsare determined on the basis of them.

Further, it is necessary to connect wirings (cables) 8 which supplycurrents from the high frequency apparatus 134, the gradient magneticfield power source 135 and so forth to the high frequency irradiatingcoil 22 and the gradient magnetic field coil 21 disposed in the recess 3as well as a shim coil disposed as required. In addition, because alarge current is supplied in a short time to the gradient magnetic fieldcoil 21 in order to obtain a gradient magnetic field of a strongintensity, it is necessary to connect a cooling pipe to the coil tosupply a refrigerant (for example, water) cooled by the heat exchanger4001 from a pump 4002 to eliminate the Joule heat generated in aconductor of the coil. Therefore, it is necessary to draw four to six ofcables 8 and two cooling pipes from the outside to the inside of therecess 3. Because the cables 8 or the cooling pipes have an outerdiameter of about 10 to 30 mm in a usual MRI apparatus, 6 to 10 of thecables or pipes require a considerable space, and if they are disposedalong a route overpassing a peripheral portion of the recess 3 of thecryostat 2, the space between the superconducting magnets 101 a and 101b is narrowed. Moreover, because the superconducting coil 12 isadjacently disposed to the peripheral portion of the recess 3 of thecryostat 2 in order to effectively generate a static magnetic field, anotch cannot be provided in the peripheral portion.

Therefore, this embodiment employs a configuration in which the cables 8and cooling pipes are passed through the through-holes 4 to draw theminto the recess 3 from the outside. That is, through-holes 71 extendingfrom the through-holes 4 of the cryostat 2 and communicating with theoutside are provided in the thick plate reinforcing member 51, and thethrough-holes 4 and the through-holes 71 are used as ducts for wiringand piping. In the example shown in FIG. 3, a through-hole 71 in theform of groove, which leads from the through-hole 4 to the outerperipheral surface, is formed on the face of the thick plate reinforcingmember 51 on the side of the cryostat 2. An opening 71 a of thethrough-hole 71 is formed at the outer peripheral surface of the thickplate reinforcing member 51. The cables 8 are drawn into thethrough-hole 71 of the thick plate reinforcing member 51 from theopening 71 a, passed through the through-hole 4 of the cryostat 2, drawninto the recess 3 and connected to the gradient magnetic field coil 21,the high frequency irradiating coil 22 and so forth. Further, althoughnot shown in the drawing, the cooling pipes are also drawn into theinside of the recess 3 and connected to the gradient magnetic field coil21 by passing them through other through-hole 4 and through-hole 71.

The cables 8 and cooling pipes can be thereby connected to the gradientmagnetic field coil 21, the high frequency irradiating coil 22 and soforth without passing them through the space between two of thesuperconducting magnets 101 a and 101 b. Therefore, the space betweentwo of the superconducting magnets 101 a and 101 b can be maintained tobe wide, and open feeling can be given to the subject 129. In addition,access to the subject 129 by an operator also becomes easy.

As described above, according to the configuration of this embodiment,the gradient magnetic field coil 21, the high frequency irradiating coil22 and so forth can be disposed in the recess 3 of the cryostat 2, andthe cables 8 and cooling pipes can be drawn into the recess 3 throughthe through-holes 4 of the cryostat 2. Therefore, the space between twoof the superconducting magnets 101 a and 101 b can be maintained to bewide, and open feeling can be given to the subject 129. In addition,because the walls 31 b and 33 b of the through-holes 4 act as columnswhich support the opposing face 25, generation of vibration in theopposing face 25 due to vibration transmitted from the gradient magneticfield coil 21 can be suppressed. Therefore, it is not required toprovide a notch at a peripheral portion of the opposing face 25 to drawthe cables 8 and so forth or thicken the opposing face 25 forsuppression of vibration, and thus the effect of maintaining opennessand the effect of suppressing vibration can be simultaneously obtainedwithout affecting the generation of the static magnetic field region 9by the superconducting coil 12.

The thick plate reinforcing member 51 can be made to have a thicknessof, for example, several tens centimeters, and as the material thereof,stainless steel etc. can be used. The number of the through-holes 4 inthe cryostat 2 can be three or more, and they can be provided atpositions in point symmetry. Further, the diameter of the through-hole 4is desirably about 15% or less of the diameter of the cryostat 2. Thisis because if the diameter of the through-hole 4 becomes large, althoughthe structural strength of the cryostat 2 increases, the surface areabecomes large, and thus the amount of heat permeating into therefrigerant container 33 increases. In this embodiment, specifically,three of the through-holes 4 are provided, and they have a diameter ofabout 100 mm. The diameter of the cryostat 2 is slightly less than 2 m,which is similar to that in a usual MRI apparatus. If the diameter ofthe through-hole 4 is about 100 mm, the rate of the wall surface area ofthe cryostat 2 increased due to formation of the through-holes 4 issmall, and the heat insulating effect of the cryostat 2 is hardlyreduced. Further, if the through-holes 4 have a diameter of about 100mm, it is possible to pass each of the cables 8 and cooling pipesthrough them.

Although the configuration that the thick plate reinforcing member 51and the cryostat 2 are provided as separate members and fixed byanchorage or the like is used in the aforementioned embodiment, it isalso possible to form the thick plate reinforcing member 51 and thecryostat 2 as one member by thickening the wall of the cryostat 2 on theside of the non-opposing face 26 (bottom) so as to be similar to thethickness of the plate reinforcing member 51.

Further, although the cables 8 and so forth are drawn to the outerperipheral surface from the through-hole 71 provided in the thick platereinforcing member 51 in the example shown in FIG. 3, it is of coursealso possible to use a configuration that the through-holes 71penetrating the thick plate reinforcing member 51 along the thicknessdirection are provided, and the cables 8 and cooling pipes are drawn outfrom the back surface of the thick plate reinforcing member 51. In thiscase, as for the lower superconducting magnet 101 b, the cables 8 andcooling pipes can be easily drawn out by providing legs for the thickplate reinforcing member 51 to secure a space between the thick platereinforcing member 51 and floor.

It is also possible to fix the cables 8 or cooling pipes to the wallsurfaces of through-holes 4 and 71 by providing a cushioning memberbetween the wall surface of the through-hole 4 or 71 and the cable 8 orcooling pipe, or filling the space with an adhesive. Transmission ofvibration of the gradient magnetic field coil 21 to the superconductingmagnet 101 a or 101 b via the cables 8 and cooling pipes can be therebyreduced.

Further, in this embodiment, because the cryostat 2 is cooled to aliquid helium temperature, the dual structure of the wall of thethrough-hole 4 consisting of the wall 31 b of the vacuum vessel 31 andthe wall 33 b of the refrigerant container 33 is used. However, when thesuperconducting coil group 11 is not required to be cooled to a liquidhelium temperature, it is also possible to use a single structurewithout providing the wall 33 b of the refrigerant container 33.

In addition, the cables from the superconducting magnets to the gradientmagnetic field power source 135 and the high frequency apparatus 134 aregenerally disposed at a position near the floor, the cables 8 andcooling pipes connected to the upper superconducting magnet 101 a can bedisposed so that they should be drawn in contact with the side surfaceof the connecting column 6 and reach the upper superconducting magnet101 a.

Second Embodiment

The MRI apparatus according to the second embodiment of the presentinvention will be explained by referring to FIGS. 4, 5(a) and (b). TheMRI apparatus according to the second embodiment uses a grid reinforcingmember 52 as a reinforcing member fixed to the cryostat 2 instead of thethick plate reinforcing member 51 used in the first embodiment. Theother structure is the same as that of the first embodiment. By usingthe grid reinforcing member 52, it is possible to further reduce theweight compared with the case of using the thick plate reinforcingmember 51 while enhancing the rigidity of the cryostat 2. Further, byproviding the through-hole 4 at a position corresponding to an openingof the grid, the cables 8 or cooling pipes can be drawn out to the backsurface side without providing through-holes in the grid reinforcingmember 52. Further, even when the cables 8 etc. are drawn out to theouter peripheral surface side of the grid reinforcing member 52, it issufficient that only a certain number of through-holes 72 should beprovided for the grid as shown in FIG. 4, FIG. 5( a) and (b), and thusprocessing becomes easy. However, in order to enhance the vibrationsuppressing effect, the number of the through-holes 72 and the diameterthereof are desirably made as small as possible.

Third Embodiment

The MRI apparatus of the third embodiment will be explained by referringto FIG. 6. Although the MRI apparatus of the third embodiment uses athick plate reinforcing member 51 as a reinforcing member like the firstembodiment, a thick plate reinforcing member 51 consisting of aplurality of separate members is used. In the example shown in FIG. 5,the circular thick plate reinforcing member 51 is divided into two ofmembers 51 a and 51 b in a semicircular shape beforehand, and themembers 51 a and 51 b are disposed so that a gap 73 should be securedbetween them and the opening of the through-hole 4 of the cryostat 2should locate between them. The gap 73 can be thereby used as a pathwayfor disposing the cables 8 or cooling pipes. Therefore, it is notnecessary to form a through-hole 71 like the thick plate reinforcingmember 51 shown in FIG. 3, resulting in an advantage that manufacture ofthe thick plate reinforcing member 51 becomes easy.

In the example shown in FIG. 6, the gap 73 is provided so that it shouldacross the center of the thick plate reinforcing member 51. However, theconfiguration of the gap 73 is not limited to this, and the gap 73 isdesirably designed considering the vibration frequency of the cryostat2, characteristic vibration frequency of the thick plate reinforcingmember 51 and so forth so that it should be disposed at an optimalposition in view of suppression of vibration.

Fourth Embodiment

The MRI apparatus of the fourth embodiment will be explained byreferring to FIG. 7. The MRI apparatus of the fourth embodiment has astructure in which not only the recess 3 is provided on the side ofopposing face 25 of the cryostat 2, but also a recess 104 is provided onthe side of the non-opposing face 26. For the non-opposing face 26, thegrid reinforcing member 52 is disposed. The grid reinforcing member 52is also disposed inside the recess 104.

In general, as already described for the first embodiment, as for thesuperconducting coil group 11 of the active sealed type, thesuperconducting coil 12 is disposed on the side of the opposing face 25near the uniform static magnetic field region 9, and the superconductingcoil 14 for correction is also disposed on the side of the opposing face25. And the superconducting coil 13 for shielding is disposed on theside of the non-opposing face 26. Therefore, because no coil is disposedat the center of the non-opposing face 26, the recess 104 can beprovided in this portion. Therefore, the grid reinforcing member 52 canbe disposed also in the recess 104, and thus the superconducting magnets101 a and 101 b can be made thinner. Accordingly, the same rigidity asthat obtained by the configuration having no recess 104 shown in FIG. 4can be obtained with thinner superconducting magnets 101 a and 101 b.More compact superconducting magnets 101 a and 101 b can be thusprovided.

Further, by using a large height of the recess 104, it becomes possibleto use a large curvature radius for bending the cables 8 and piping.Therefore, it also becomes possible to easily dispose even a cablehaving a large outer diameter such as the cables 8 of the gradientmagnetic field coil 21 and so forth requiring a large current.

In addition, it is also possible to dispose a thick plate reinforcingmember 51 of the structure shown in FIG. 2 or a thick plate reinforcingmember 51 of the structure shown in FIG. 6 instead of the gridreinforcing member 52 shown in FIG. 7.

Fifth Embodiment

The MRI apparatus of the fifth embodiment will be explained by referringto FIG. 8. In the MRI apparatus of the fifth embodiment, three or morethrough-holes 4 are provided in the cryostat 2, and three ofthrough-holes 71 connected to three of the through-holes 4,respectively, are radially provided in the thick plate reinforcingmember 51. In three of the through-holes 71, cables 81 to the gradientmagnetic field coil 21, cables 82 to the high frequency irradiating coil22 and a cooling pipe 83 to the gradient magnetic field coil 21 arepassed through, respectively. By such a configuration, the cables 81 andthe cables 82 do not approach each other, influence of inductionmagnetic field produced by the cables 81 connected to the gradientmagnetic field coil 21, in which a large current flows, on signalsflowing in the cables 82 connected to the high frequency irradiatingcoil 22 can be prevented. Further, because the through-hole 71 in whichthe cooling pipe 83 is disposed is different from the through-holes 71in which the cables 81 and 82 disposed, respectively, even if leakage ofwater occurs in the cooling pipe 83, there should be no possibility ofwetting of the cables 81 and 82 with water.

Further, because the symmetry of the rigidity of the thick platereinforcing member 51 can be increased by the radial disposition of thethree through-holes 71, even if vibration behavior of the gradientmagnetic field coil 21 changes depending on the axis of the gradientmagnetic field generated by the gradient magnetic field coil 21,vibration can be suppressed irrespective of the axial direction.

In the configuration shown in FIG. 8, three or more through-holes 4 areprovided in the cryostat 2, and the cables 81 and 82 and the coolingpipe 83 are drawn out from three of the through-holes 4, respectively.However, it is also possible to provide only one through-hole 4 at thecenter and draw out the cables 81 and 82 and the cooling pipe 83 fromthis one through-hole 4. In this case, the radial three through-holes 71of the thick plate reinforcing member 51 are configured to be connectedat the center. It is desirable to dispose a separation plate or the likefor electrically separating the cables 81 and 82 and the cooling pipe83, respectively, at a position at which the cables approach each other.

Sixth Embodiment

The MRI apparatus of the sixth embodiment will be explained by referringto FIGS. 9, 10 and 11. In the MRI apparatus of the sixth embodiment, asshown in FIG. 9, at least three through-holes 4 are provided in thecryostat 2, and three through-holes 71 connected with the threethrough-holes 4, respectively, are provided in the thick platereinforcing member 51. These three through-holes 71 join on the way at ameeting 71 c in the thick plate reinforcing member 51 to form a onethrough-hole 71 d of a large diameter. An opening 71 b of thethrough-hole 71 d of a large diameter is provided at the outerperipheral surface of the thick plate reinforcing member 51. Further,inside the through-hole 71 d of a large diameter, a plate or cylindricalpartition 86 for dividing the interior space into three spaces isdisposed.

The cables 81 to the gradient magnetic field coil 21, the cables 82 tothe high frequency irradiating coil 22 and the cooling pipe 83 to thegradient magnetic field coil 21 are all drawn into the through-hole 71 dof a large diameter in the thick plate reinforcing member 51 from theopening 71 b, pass through the three spaces separated by the partition86, respectively, branch at the confluence 71 c into the threethrough-holes 71, pass through the separate through-holes 4 of thecryostat 2 and drawn into the recess 3. This structure has an advantagethat because all of the cables 81 and 82 and the cooling pipe 83 aremanageable at one opening 71 b, and thus management becomes easy.

Further, in this embodiment, as shown in FIG. 11, the cables 81 and thecables 82 pass through two of perpendicularly upper spaces among thethree spaces separated by the partition 86, respectively, and thecooling pipe 83 passes through one perpendicularly lower space in theinside of the through-hole 71 d of a large diameter. The possibility ofwetting of the cables 81 and 82 is thereby eliminated, even if waterleakage occurs in the cooling pipe 83.

Furthermore, as shown in FIG. 11, the cooling pipe 83 is disposed sothat it should pass through the space under the cables 81 to thegradient magnetic field coil 21. By disposing the cooling pipe 83 asdescribed above, the Joule heat generated by the cable 81, in which alarge current flows, can be eliminated by the cooling pipe 83. Inaddition, as for the structure of the cables 81, by wiring six electricsupplying cables to X, Y and Z coils of the gradient magnetic field coil21 in rows as shown in FIG. 11, not wiring them as a bunch, coolingefficiency can be enhanced. By using a metal having a high thermalconductivity such as copper and aluminum as the material of thepartition 86, cooling efficiency can be increased. Because thispartition 86 acts also as a magnetic shield, an effect of preventinginfluence of the induction electromagnetic waves generated by the cables81 to the gradient magnetic field coil 21 on the cables 82 can also beobtained.

Seventh Embodiment

The MRI apparatus of the seventh embodiment will be explained byreferring to FIG. 12. In the MRI apparatus of the seventh embodiment, asshown in FIG. 12, the wall (bottom) of the non-opposing face 26 of thecryostat 2 is thickened to integrally form the thick plate reinforcingmember 54. This thick plate reinforcing member 54 is disposed only for aregion of doughnut shape on the peripheral side from the through-hole 4.In a region on the center side from the through-hole 4, a gridreinforcing member 56 is disposed. The rigidity of the non-opposing face26 of the cryostat 2 is thereby increased in spite of the structure thatcan be easily manufactured. In the structure shown in FIG. 12, theconnecting column 6 is omitted.

The grid reinforcing member 56 is disposed so that the positions ofopenings should correspond to the positions of the through-holes 4. Thecables 81 and 82 and the cooling pipe 83 pass through the openings ofthe grid reinforcing member 54 and the through-holes 4 and drawn intothe recess 3. Further, as shown in FIG. 12, by disposing legs 55 underthe lower superconducting magnet 101 b to provide a space with respectto the floor 57, it can be made easy to draw the cables 81 and 82 to thelower superconducting magnet 101 b and the cooling pipe 83 to the outerperipheral surface.

In the first to seventh embodiments described above, the samereinforcing structure for the cryostat 2 is used for the uppersuperconducting magnet 101 a and the lower superconducting magnet 101 b.However, because the responses of the upper and lower superconductingmagnets 101 a and 101 b to vibration of course differ, differentreinforcing structures may also be used for the upper and lowersuperconducting magnets 101 a and 101 b. For example, the gridreinforcing member 52 may be employed for the upper side, and the platereinforcing member 51 may be employed for the lower side. Further, it isalso possible to use different sizes or materials of the reinforcingmembers for the upper and lower superconducting magnets 101 a and 101 b.If a heavy load is placed on the superconducting magnet 101 a, resonanceat a low frequency generally becomes likely to occur. Therefore, as inthe embodiment shown in FIG. 12, a smaller thickness of the thick platereinforcing member 51 can be used for the upper superconducting magnet101 a compared with that for the lower superconducting magnet 101 b.

Further, in the first to seventh embodiments, the gradient magneticfield coil 21 is fixed to the cryostat 2 with the fixing part 15.However, the cryostat 2 and the gradient magnetic field coil 21 can befirmly fixed into one body by using the structures shown in the eleventhto fourteenth embodiments mentioned later. The rigidity of the cryostat2 and the gradient magnetic field coil 21 as a whole is therebyimproved, and therefore vibration of the cryostat 2 and the gradientmagnetic field coil 21 as a whole can be reduced.

Furthermore, the structures which will be shown in the eighth to tenthembodiments may be used for the first to seventh embodiments as astructure of connecting the gradient magnetic field coil 21 and thecables 8 or a structure of connecting the gradient magnetic field coil21 and the cooling pipe 83. The gradient magnetic field coil and thecables 8 or the cooling pipe 63 can be thereby easily connected, andthus manufacturing efficiency and efficiency of maintenance operationcan be improved.

Eighth Embodiment

Hereafter, the eighth embodiment of the present invention will beexplained on the basis of FIG. 13. The MRI apparatus of the eighthembodiment has the same configuration as that of the first embodimentexcept that the superconducting magnets 101 a and 101 b are not providedwith the thick plate reinforcing members 51 and 54 and the gridreinforcing members 52 and 56.

In the cryostat 2 for each of the superconducting magnets 101 a and 101b, at least one or more of through-holes 4 (in FIG. 13, twothrough-holes are provided on each of both sides) are provided at aposition(s) near the side of the recess 3 at the center, i.e., near theside of the gradient magnetic field coil 21, connecting the opposingface 25 and the non-opposing face 26. The cross-sectional shape of thethrough-hole 4 may be any one of circle, quadrangle, ellipse etc.

As shown in FIG. 14, the cables 8 for the gradient magnetic field coil21 and the high frequency magnetic field coil 22 are fixed to thethrough-hole 4. That is, at the time of forming the superconductingmagnets 101 a and 101 b, the cables 8 are fixed in the through-hole 4 bypassing them through the through-hole 4, providing a plug 207 forreserving liquid at a lower position of the hole, pouring a fixing agent208 (for example, resin, foaming agent) from the top and curing theagent. The plug 207 for reserving liquid may be made of a polymermaterial such as resin or silicone rubber, and a highly airtightmaterial is preferred.

Further, as shown in FIG. 15, the cables 8 may be fixed in a cushioningmaterial 209 (for example, cork, shock absorber), of which outer shapeis manufactured beforehand so as to fit the hole shape of thethrough-hole 4, and inserted into the through-hole 4. The cushioningmaterial 209 can be fixed in the through-hole 4 by applying an adhesiveto the outer surface of the cushioning material 209 beforehand, orpouring an adhesive after inserting it into the through-hole 4.

Further, as shown in FIG. 16, a rod-like guide 221 can be fixed to thecables 8, and a rail 222 for leading the guide 221 can be attached inthe through-hole 4. The guide 221 to which the cables 8 are fixed may belead along the rail 222 and fixed at a predetermined position.

As shown in FIG. 17, the cables 8 are connected to a current receivingterminal 211 attached to the gradient magnetic field coil 21. FIG. 18 isa view from top of the part shown in FIG. 17. At the end of each cable8, a current supplying terminal 210 is attached. The terminal 211 is acurrent receiving terminal coming from the gradient magnetic field coil.By mounting the gradient magnetic field coil 21 on the cryostat 2 fromthe top so that the current receiving terminal 211 should besuperimposed on the current supplying terminal 210 and fastening theterminals 210 and 211 with a bolt 212, the gradient magnetic field coil21 and the cable 8 can be connected. Thus, the fastening position can beaccessed from a position above the recess 3 and therefore observed withgood visibility, and operation for the fastening with the bolt can beeasily performed. Further, because the cable 8 and the gradient magneticfield coil 21 can be separated only by removing the bolt 212, thegradient magnetic field coil 21 can also be easily removed.

Further, the terminals 210 and 211 may be electrically contacted byusing a connector, without fastening them with the bolt 212 as shown inFIG. 17. An example is shown in FIG. 19, in which a connector 213 isused as the current supplying terminal 210, and a connector 214 is usedas the current receiving terminal 211. As the connectors 213 and 214,for example, the product of Multi-Contact having a trade name of “Forkplug” can be used.

Although the eighth embodiment is as described above, anotherconfiguration can be employed, in which the cables 8 are attached to thegradient magnetic field coil 21 beforehand, and when attaching thegradient magnetic field coil 21 to the superconducting magnet 101 a or101 b, the cables 8 are fixed to the through-hole 4. In this case, whenthe gradient magnetic field coil 21 is attached to the cryostat 2, thecables 8 attached to the gradient magnetic field coil 21 are passedthrough the through-hole 4. A manner therefor would be, for example,that a member serving as the guide 221 in the shape of rod or the likeis temporarily fixed to the cables 8 and the guide 221 is passed alongthe rail 222 provided in the through-hole 4. Then, the plug 207 forreserving liquid is disposed at a lower part of the through-hole 4, andthe fixing agent 208 is poured from above and cured.

Alternatively, it is also possible to pass only the guide 221 throughthe through-hole 4 without using the rail 222, dispose the plug 207 forreserving liquid at a lower position of the through-hole 4, pour afixing agent 208 from the top and cure the agent. Further, it is alsopossible to temporarily fix the cables 8 at the end of the guide 221 andafter used as a guide at the time of passing the cables through thethrough-hole 4, remove the guide 221.

In the eighth embodiment, the wall of the through-hole 4 provided in thecryostat 2 acts as a column, and the rigidity of the cryostat 2 as awhole can be thereby improved. Thus, vibration of the superconductingmagnets 101 a and 101 b can be reduced. Further, because the spacebetween the cables 8 and the wall surface of the through-hole 4 isfilled with the cushioning material 209 or fixing agent 208 to fix thecables 8, transmission of vibration of the gradient magnetic field coil21 to the superconducting magnet 101 a or 101 b via the cables 8 can bereduced. There can be a further advantage that when the cables 8 arepassed through the through-hole 4, the connection operation becomes easyby using the terminals 210, 211 and so forth.

In addition, it is of course also possible to fix any one of the thickplate reinforcing members 51 and 54 and grid reinforcing members 52 and56 described in the first to seventh embodiments to the cryostat 2. Insuch a case, because the rigidity of the cryostat 2 can be furtherimproved, vibration of the superconducting magnets 101 a and 101 b canbe further reduced.

Ninth Embodiment

Hereafter, the ninth embodiment of the present invention will beexplained on the basis of FIG. 20. Also in this embodiment, thesuperconducting magnets 101 a and 101 b are not provided with the thickplate reinforcing member 51 and so forth and the grid reinforcing member52 and so forth as in the eighth embodiment.

In the cryostat 2 of the superconducting magnet 101 a or 101 b shown inFIG. 20, at least one through-hole 4 (in FIG. 20, one through-hole isprovided) is provided, which connects the opposing face 25 and thenon-opposing face 26 at the center of the central portion of the recess3. The configuration other than the connection terminals is the same asthat of the structure shown in FIG. 13 according to the eighthembodiment.

A connecting structure for the cables 8 and the gradient magnetic fieldcoil 21 according to this embodiment is shown in FIG. 21. A terminal 215is a current supplying terminal attached to the end of each cable 8, andit has a hollow 215 a. Although this hollow 215 a has a circularcross-section in this example, it does not need to be circular, and itmay have a polygonal shape. A terminal 216 is a current receivingterminal attached to the gradient magnetic field coil 21, and has aprojection 216 a to be inserted into the circular hollow 215 a of theterminal 215. By inserting the projection 216 a of the current receivingterminal 216 into the hollow 215 a of the current supplying terminal215, the gradient magnetic field coil 21 can be connected to the cable8. By using such a structure, the cables 8 can be connected to thecentral part of the superconducting magnet 101 a or 101 b, and removalthereof also becomes easy. As such a terminal structure, for example,the products of Multi-Contact having trade names of “B10N Socket” and“S10N Plug” can be used. Furthermore, a detachable and attachableconnector of lock-type (for example, the products of Multiple Connectorhaving trade names of “B10AR-N Socket” and “S10AR-N Plug”) or such aconnecter as shown in FIG. 19 that can be perpendicularly connected mayalso be used.

As another example of the ninth embodiment, the cables 8 may be attachedto the gradient magnetic field coil 21 in advance, and when attachingthe gradient magnetic field coil 21 to the superconducting magnet 101 aor 101 b, the cables 8 are fixed to the through-hole 4. In this case,the cables 8 attached to the gradient magnetic field coil 21 beforehandare passed through the through-hole 4 when the gradient magnetic fieldcoil 21 is attached to the superconducting magnet 101 a or 101 b. Amanner therefor may be to fix the cushioning material 217 manufacturedbeforehand into an outer shape corresponding to the inner shape of thethrough-hole 4 to the cables 8, and to insert the cushioning material217 into the through-hole 4 as shown in FIG. 22. The cushioning material217 can be fixed in the through-hole 4 with an adhesive appliedbeforehand to the outer surface of the cushioning material 217.

The connection of the cables 8 to the gradient magnetic field coil 21was explained above. Connection of the cables 8 with the high frequencymagnetic field coil 22 or a shim coil can also be attained in a similarmanner. In such a case, a plurality of through-holes 4 may be provided,and individual cables 8 or grouped cables 8 may be passed through thethrough-holes 4, respectively. Alternatively, all the required cables 8can be bundled and fixed in the through-hole 4 as one bunch.

Tenth Embodiment

Hereafter, a connecting structure of a piping 2208 for supplying arefrigerant for cooling the gradient magnetic field coil 21 will beexplained as the tenth embodiment by referring to FIG. 23. Thisstructure can be used independently or in combination with theconnecting structures of the cables 8 explained in the eighth and ninthembodiments.

A structure for connecting the piping 2208 and the gradient magneticfield coil 21 with terminals 2101 and 2100 at a lateral position of thegradient magnetic field coil 21 is shown in FIG. 23. The terminal 2100is a refrigerant supplying terminal attached to the end of the piping2208, and the terminal 2101 is a refrigerant receiving terminal attachedto the gradient magnetic field coil 21.

A hollow through-hole 2208 a is provided in the piping 2208 and theterminals 2100 and 2101. The cross-sections of the piping 2208 and theterminals 2100 and 2101 may have a quadrangular or circular shape. Anend projection 2100 a of the refrigerant supplying terminal 2100 isinserted into a hollow 2100 a provided in the refrigerant receivingterminal 2101. By using a detachable and attachable lock type connector2102 as shown in FIG. 24 as these terminals 2100 and 2101, a detachableand attachable structure can be obtained.

Alternatively, as shown in FIG. 25, when a rubber tube 2105 is used asthe piping 2208, the refrigerant supplying terminal 2100 may be omitted,and the piping 2208 may be fixed by constricting a fixing band 2103 witha screw 2104. As an example of such terminal 2101 and band 2103, theproduct of Staubli having a trade name of “Quick Release Coupling” canbe used.

Further, when the refrigerant supplying terminal 2100 and therefrigerant receiving terminal 2101 made of a nonmagnetic metallicsubstance (brass, stainless steel etc.) are used, the both may be fixedby brazing. Alternatively, the connector of Swagelok may be used, withwhich the piping 2208 and the terminals 2100 and 2101 are fixed byrotating a nut 2106 as shown in FIG. 26.

By using such a configuration as described above, the gradient magneticfield coil 21 can be cooled by cooling the refrigerant outside thegradient magnetic field coil 21 and circulating the refrigerant (liquidor gas) in the piping 2208. Furthermore, when the piping 2208 andterminals 2100 and 2101 made of a conductive material are used, theelectric current from the gradient magnetic field power source 135 canbe supplied to the piping 2208 also having the function of the cables 8to supply electric power to the gradient magnetic field coil 21.

The structure for connecting the piping 2208 at a lateral position ofthe gradient magnetic field coil 21 was explained above. However, thestructure can also be applied to connection at a central position of thegradient magnetic field coil 21 as shown in FIG. 27.

According to the eighth to tenth embodiments, connection of cables 8 forsupplying electric currents to the gradient magnetic field coil, highfrequency magnetic field coil and shim coil and receiving echo signalsand fixation and connection of piping for supplying a refrigerant forcooling the gradient magnetic field coil can be easily attained withoutdegrading open feeling in an MRI apparatus. In addition, the gradientmagnetic field coil, high frequency magnetic field coil and shim coilcan be easily detached and attached during maintenance operations.

Further, because the through-hole 4 prepared in the cryostat 2 of thesuperconducting magnet 101 a or 101 b acts as a column, rigidity of thecryostat 2 can be enhanced, and therefore vibration of superconductingmagnet 101 a or 101 b due to vibration of the gradient magnetic fieldcoil 21 can be suppressed. Moreover, by fixing the cables 8 and piping2208 to the inner wall surface of the through-hole 4 with a cushioningmaterial 217 or fixing agent 208, transmission of vibration of thegradient magnetic field coil 21 to the superconducting magnet 101 a or101 b via the cables 8 and the piping 2208 can be reduced. Thus,vibration of the superconducting magnets 101 a and 101 b can be reduced.

In addition to the configurations of the eighth to tenth embodiments, astructure reinforcing member such as the thick plate reinforcing members51 and 54 and the grid reinforcing members 52 and 56 of the first toseventh embodiments may of course be also fixed. In this case, therigidity of the cryostat 2 can be further enhanced, and thereforevibration of the superconducting magnets 101 a and 101 b can be furtherreduced.

Eleventh Embodiment

In the eleventh embodiment, the gradient magnetic field coil 21 isfirmly fixed on the superconducting magnet 101 a or 101 b having therigidity-enhancing structure and rigidly formed to reduce the vibrationamplitude of the gradient magnetic field coil 21. As a result, thevibration amplitude of the superconducting magnets 101 a and 101 b isalso reduced. At the same time, generation of noise caused by thevibration is also suppressed. Although the structure of thesuperconducting magnets 101 a and 101 b is the same as that of the firstembodiment, the thick plate reinforcing member 51 and so forth are notprovided.

The eleventh embodiment will be explained by referring to FIG. 28. Thegradient magnetic field coil 21 is fixed to the opposing surface 25 ofthe cryostat of the superconducting magnet 101 a or 101 b with fixingmembers 3203. Although the weight of the gradient magnetic field coil 21considerably changes depending on the structure and material thereof, itis generally comparatively heavy, i.e., as heavy as about 30 to 400 kg.In this embodiment, the vibration amplitude of the gradient magneticfield coil 21 is reduced by firmly fixing the gradient magnetic fieldcoil 21 to the cryostat 2. As a result, the vibration amplitude of thesuperconducting magnets 101 a and 101 b is reduced, and generation ofnoise is also suppressed at the same time.

That is, by firmly fixing the gradient magnetic field coil 21 and thecryostat 2 into one body, the rigidity as a whole can be enhancedcompared with the case where they are not integrated. As a result, whenthe Lorentz force acts at the same level, the vibration amplitude ofthem can be suppressed to a smaller degree compared with the case wherethey are not integrated. In addition, in this embodiment, in order toimprove the rigidity as a whole, a plate made of a material having ahigh Young's modulus (for example, glass reinforced epoxy plate etc.) isclosely adhered as a gradient magnetic field coil reinforcing member3205 to the gradient magnetic field coil 21 on the side of the opposingsurface 325. For this attachment, adhesion, integral molding of theplate and the gradient magnetic field coil 21 and so forth can be used.

Further, it is desirable to make the wall of the cryostat 2 on the sideof the opposing face 25 as thick as the other conditions for design suchas strength and uniformity of the magnetic field in the imaging volume(uniform static magnetic field region 9) allow, and a thicker wallimproves the total rigidity. Furthermore, although the fixing member3203 is disposed only for the peripheral portion of the gradientmagnetic field coil 21 in FIG. 28, in order to promote the integration,it is desirable to dispose it also at the central portion of thegradient magnetic field coil 21. Alternatively, it is also possible toanchor the gradient magnetic field coil 21 to the cryostat 2 byadhesion.

The fixing member 3203 fixing the gradient magnetic field coil 21penetrates the gradient magnetic field coil reinforcing member 3205 andthe gradient magnetic field coil 21, and is firmly fixed to the cryostat2. The gradient magnetic field coil reinforcing member 3205 and thegradient magnetic field coil 21 are thereby fixed to the cryostat 2.Through-holes 3203 a for passing the fixing member 3203 are provided inthe gradient magnetic field coil 21. The through-hole 3203 a desirablyhas such a diameter that the side wall of the through-hole 3203 a shouldnot substantially contact with the fixing member 3203. This is becauseif the fixing member 3203 contacts with the side wall of thethrough-hole 3203 a, fixing condition of the gradient magnetic fieldcoil 21 fluctuates depending on the position or degree of the contact,thus vibration mode differs in every MRI apparatus, and it becomesimpossible to obtain stable performance. As the fixing member 3203, abolt can be used, and in such a case, a tapped hole is provided in thecryostat 2 as the receiving side. When a sufficient thickness forproviding the tapped hole cannot be secured for the cryostat 2, a base3250 having the configuration shown in FIG. 32 mentioned later can beemployed.

As described above, the MRI apparatus of the eleventh embodiment canmake the vibration amplitude of the gradient magnetic field coil 21smaller by fixing the gradient magnetic field coil 21 and the cryostat 2into one body to increase the rigidity of the gradient magnetic fieldcoil 21 and cryostat 2 as a whole. The amplitude of vibrationtransmitted from the gradient magnetic field coil 21 to the cryostat 2can be thereby made smaller compared with the case where they are notintegrated, and thus vibration of the superconducting magnets 101 a and101 b can be suppressed.

In addition to the configuration of the eleventh embodiment, a structurereinforcing member such as the thick plate reinforcing members 51 and 54and the grid reinforcing members 52 and 56 of the first to seventhembodiments may of course be also fixed. In this case, the rigidity ofthe cryostat 2 can be further enhanced, and therefore vibration of thesuperconducting magnets 101 a and 101 b can be further reduced.

Twelfth Embodiment

FIGS. 29( a) and (b) show the MRI apparatus of the present inventionaccording to the twelfth embodiment. Although only the lowersuperconducting magnet 101 b is shown in FIGS. 29( a) and (b) forsimplicity, the upper superconducting magnet 101 a also hassubstantially the same structure, and each component is disposed in aperpendicularly symmetric manner with respect to the horizontal plane atthe center of the imaging volume (uniform static magnetic field region9). In this embodiment, the gradient magnetic field coil 21 comprises,from the imaging space side, a main coil 3213 for generating a gradientmagnetic field, an intermediate member 3211 and a shield coil 3214 forpreventing leakage of the gradient magnetic field to the outside.

The configuration shown in FIG. 29( a) has a structure that, in order toenhance the rigidity of the whole cryostat 2, the wall of the opposingface 25 and the wall of the non-opposing face 26 of the cryostat 2 arefirmly linked with cryostat reinforcing members 3210. The reason of thisis as follows. That is, because the non-opposing face 26 does not facethe uniform static magnetic field region 9 unlike the opposing face 25,there is a dimensional margin to a certain extent, and therefore it iscomparatively easy to thicken the wall of the non-opposing face 26.Therefore, by linking the wall of the opposing face 25 with the wall ofthe non-opposing face 26, of which rigidity is increased by thickeningthe wall, with the cryostat reinforcing members 3210, the rigidity ofthe wall on the side of the opposing face 25 can be increased.

Further, in the configuration shown in FIG. 29( b), through-holes 4penetrating the cryostat 2 are provided instead of the reinforcingmembers 3210 shown in FIG. 29( a). Because the side walls of thethrough-holes 4 link the opposing face 25 and the non-opposing face 26of the cryostat 2, the rigidity of the wall on the side of the opposingface 25 can be increased as in the configuration shown in FIG. 29( a).Further, in the configuration shown in FIG. 29( b), because the recess 3is provided for the opposing face 25, the gradient magnetic field coil21 can be disposed in the recess 3 and fixed to the cryostat 2. Thisallows reduction of the thickness of the superconducting magnet 101 b sothat a wide imaging volume can be maintained.

Further, in the configurations shown in FIGS. 29( a) and (b), the fixingmember 3203 is put into a spot-faced hole 3212 provided in anintermediate material 3211 and fixed to the cryostat 2. The length ofthe fixing member 3203 can be thereby shortened. The integration of thegradient magnetic field coil 21 and the cryostat 2 can be furtherimproved, and the rigidity of the gradient magnetic field coil 21 andthe cryostat 2 can be improved. In the configurations shown in FIGS. 29(a) and (b), the gradient magnetic field coil 21 has a main coil 3213 anda shield coil 3214, and because the diameter of the main coil 3213 isgenerally smaller than that of the shield coil 3214, the peripheralportion of the gradient magnetic field coil 21 can be fixed to thecryostat 2 as shown in FIGS. 29( a) and (b). When the center portion ofthe gradient magnetic field coil 21 is fixed to the cryostat 2, a longfixing member 3203 can be used as shown in FIG. 28.

In order to shorten the fixing member 3203 even in the center portion,it is possible to employ the structure shown in FIG. 32. FIG. 32 shows apartial section of the gradient magnetic field coil 21, in which a fixedbolt as the fixing member 3203 is accommodated in the intermediatematerial 3211. The fixing bolt can be manipulated through a hole 3213 aprovided in a part of the main coil 3213. When a bolt is used as thefixing member 3203, the wall of the cryostat 2 as the receiving sideshould have a thickness larger than a certain thickness. If a sufficientwall thickness cannot be secured for the cryostat 2, the base 3250 shownin FIG. 32 mentioned later can be employed.

As described above, in the configurations shown in FIGS. 29( a) and (b)according to the twelfth embodiment, the gradient magnetic field coil 21has a three-layer structure, the wall thickness of the non-opposing face26 of the cryostat 2 is increased, and the cryostat reinforcing member3210 or the through-hole 4 is further provided, and in addition, thegradient magnetic field coil 21 and the cryostat 2 are integrated byfixation. Thereby, the rigidity of the gradient magnetic field coil 21and the cryostat 2 as a whole is further increased, and thereforevibration of the superconducting magnets 101 a and 101 b can be furtherreduced. It is not necessary to use all of the structures, thethree-layer structure for the gradient magnetic field coil 21, thestructure of thickened wall of the non-opposing face 26 of the cryostat,and the structure with the cryostat reinforcing member 3210 or thethrough-hole 4. One or more of the structures can be used.

In addition to the configuration of the twelfth embodiment, a structurereinforcing member such as the thick plate reinforcing members 51 and 54and the grid reinforcing members 52 and 56 of the first to seventhembodiments may of course be also fixed. In this case, the rigidity ofthe cryostat 2 can be further enhanced, and therefore vibration of thesuperconducting magnets 101 a and 101 b can be further reduced.

Thirteenth Embodiment

The thirteenth embodiment of the MRI apparatus according to the presentinvention is shown in FIG. 30. In this embodiment, a through-hole 3251is provided at the center part in order to strengthen the opposing face25 side of the cryostat 2. The side wall 3251 a of this through-hole3251 plays a role of a column, and therefore it can improve the rigidityof the wall of the opposing face 25. The position of the through-hole3251 is not limited to the central part as shown in FIG. 30. It may beprovided at an off-center position, or a plurality of the holes may beprovided. The thus provided through-hole 3251 can be also used as apathway of the cables 8 (not shown in FIG. 30) or a piping for cooling.Alternatively, the gradient magnetic field coil 21 can also be anchoredto the cryostat 2 using atmospheric pressure by increasing sealingbetween the through-hole 3251 and the gradient magnetic field coil 21and decompressing the inside of the through-hole 3251 to vacuum. In thiscase, an advantage is provided, i.e., the structure concerning thefixation part on the side of the gradient magnetic field coil 21 issimplified.

Further, in the structure shown in FIG. 30, a nonmagnetic insulatingmember 3220 and a nonmagnetic conductive member 3221 are disposedbetween the gradient magnetic field coil 21 and the cryostat 2 havingthe same structures as those used in the eleventh embodiment. Thenonmagnetic conductive member 3221 produces an eddy current insideinduced by temporal fluctuation of a static magnetic field and therebysuppresses the temporal fluctuation of a static magnetic field caused byvibration of the superconducting magnets 101 a and 101 b and so forth.This technique is described in, for example, WO02/071942. Thenonmagnetic conductive member 3221 preferably consists of a materialhaving a high electric conductivity such as aluminum and copper. A holecan be provided in this nonmagnetic conductive member 3221 so that itcan also be used as a tray for disposing a shim material. Thisnonmagnetic conductive member 3221 preferably has a thickness of aboutseveral millimeters to 30 mm.

The nonmagnetic insulating member 3220 produces the interval between ofa coil pattern portion of the gradient magnetic field coil 21 andelectric conductor portions such as the nonmagnetic conductive member3221 to suppress generation of excessive eddy current in the nonmagneticconductive member 3221. Degradation of image quality is therebyprevented. That is, while the pattern of the shield coil 3214 isdesigned so as to prevent the eddy current generated by the gradientmagnetic field coil 21, if the distance with respect to the nonmagneticconductive member 3221 is too small, the eddy current cannot besufficiently suppressed. Therefore, by increasing the interval betweenthe coil pattern portion of the gradient magnetic field coil 21 andelectric conductor portions such as the nonmagnetic conductive member3221, the aforementioned problem can be solved, and degradation of imagequality can be prevented. As the nonmagnetic insulating member 3220becomes thicker, the eddy current suppressing effect increases. However,the other components must be made thinner in order to secure an openspace. Therefore, the actual thickness is preferably about severalmillimeters to ten and several millimeters. Further, it is also possibleto dimensionally effectively use this portion by disposing a shim coilby molding etc.

In this thirteenth embodiment, the aforementioned members 3220 and 3221inserted between the gradient magnetic field coil 21 and the cryostat 2must be firmly integrated to the wall surface of the cryostat 2 togetherwith the gradient magnetic field coil 21. For this purpose, for example,the nonmagnetic conductive member 3221 and the cryostat 2 can beanchored beforehand by adhesion, welding or the like, or the nonmagneticconductive member 3221 can be formed as a cladding material of thecryostat 2. The cladding material referred to here is a compositematerial consisting of different metals rolled into one plate forbringing out the best characteristics of each material. In thisembodiment, a stainless steel material, which is a common material forthe cryostat 2, and a material having a high electric conductivity suchas aluminum and copper used for the nonmagnetic conductive member 3221are made into a composite material. The purpose of each member isthereby attained, and at the same time, the rigidity can be improved byintegration of both of the members. Further, it is also possible tointegrate the nonmagnetic insulating member 3220 and the gradientmagnetic field coil 21 by adhesion, molding or the like, and workabilityfor attachment etc. is also thereby improved.

By providing the through-hole 4 in the cryostat 2 to increase therigidity of the cryostat 2 and fixing the gradient magnetic field coil21 to the cryostat 2 to integrate them as in the thirteenth embodiment,vibration of the superconducting magnets 101 a and 101 b can be reduced.Further, by disposing the nonmagnetic conductive member 3221 and thenonmagnetic insulating member 3220, the magnetic characteristics of thesuperconducting magnets 101 a and 101 b can be improved.

In addition to the configuration of the thirteenth embodiment, astructure reinforcing member such as the thick plate reinforcing members51 and 54 and the grid reinforcing members 52 and 56 of the first toseventh embodiments may of course be also fixed. In this case, therigidity of the cryostat 2 can be further enhanced, and thereforevibration of the superconducting magnets 101 a and 101 b can be furtherreduced.

Fourteenth Embodiment

The fourteenth embodiment of the MRI apparatus of the present inventionis shown in FIGS. 31( a) and (b). An enlarged view of a central fixationpart 3204 shown in FIG. 31( a) is shown in FIG. 31( b). In thisembodiment, a splitnut 3301 is used for attaching the gradient magneticfield coil 21. The splitnut 3301 is anchored to the wall of the cryostat2 beforehand by welding, adhesion or the like. The nonmagneticinsulating member 3220 have been anchored to the gradient magnetic fieldcoil 21. By inserting a tapered screw 3302 into the splitnut 3301, theouter periphery of the nut 3301 is expanded and pushes the inner surfaceof the nonmagnetic insulating member 3220, and thus fixation isattained. By using a tapered shape for the inner circumference surfaceof the nut 3301 instead of using the screw 3302, the same effect can beobtained. This fixing method has an advantage that the manufacture ofthe gradient magnetic field coil 21 becomes easy, because diameter ofholes provided in the main coil 3213 and the intermediate material 3211can be made small. Although the nonmagnetic conductive member 3221 isnot shown in FIGS. 31( a) and (b), it is of course also possible todispose the nonmagnetic conductive member 3221.

FIG. 32 shows an embodiment where a fixing bolt is used as the fixingmember 3203, and the fixing bolt 3203 is fixed by using a base 3250. Theintermediate member 3211 is provided on the imaging space side with ahole 3211 a for accommodating the head portion of the fixing bolt 3203,and the remaining portion of intermediate material 3211 and the shieldcoil 3214 are provided with a through-hole 3214 a through which theportion of the fixing bolt 3203 under the head can penetrate. Thisthrough-hole 3214 a desirably has such an inner diameter that the wallsurface of the hole should not substantially contact with the fixingbolt 3203. Further, the cryostat 2 as the receiving side is providedwith a tapped hole. For this purpose, the cryostat 2 should have a wallthickness of a certain level or larger. When a sufficient thicknesscannot be secured for the cryostat 2, a base 3250 is installed on thecryostat 2 on the opposing face 25 side, and the nonmagnetic insulatingmember 3220 is provided with a hole 3220 a in which the base 3250 can beaccommodated. By using these configurations, the intermediate material3211 and the shield coil 3214 are fixed by pinching them between thehead portion of the fixing bolt 3203 and the cryostat 2.

Although embodiments where the present invention is applied to the MRIapparatus having a pair of superconducting magnets perpendicularlydisposed as a static magnetic field generating source are explainedabove, the MRI apparatus of the present invention is not limited to theaforementioned embodiments, and various modifications are possible. Forexample, the same structures may also be used for a coil for resistivetype magnet. Further, the pair of static magnetic field generatingsources may also be configured to be horizontally disposed.

Furthermore, although each embodiment was individually explained, aconfiguration utilizing the configurations of two or more of theembodiments in combination is also possible. For example, it is possibleto combine the twelfth and thirteenth embodiments to provide both thecryostat reinforcing member 3210 and the through-hole 3251 for thecryostat 2 and thereby enhance the rigidity of the cryostat 2. Further,it is also possible to combine the eleventh and twelfth embodiments toput the gradient magnetic field coil reinforcing member 3205 of theeleventh embodiment on the gradient magnetic field coil 21 of thetwelfth embodiment and thereby enhance the rigidity of the gradientmagnetic field coil 21.

1. A magnetic resonance imaging apparatus comprising a pair of staticmagnetic field generating sources opposingly disposed on both sides ofan imaging space and gradient magnetic field generating part disposed onthe imaging space side of each static magnetic field generating sourcefor applying a gradient magnetic field to the imaging space, wherein thestatic magnetic field generating sources each comprise a magnetic fieldgenerating coil and a closed vessel enclosing the magnetic fieldgenerating coil inside, the gradient magnetic field generating part issupported on a face of the closed vessel on the imaging space side, atleast one of the closed vessel has a rigid structure for preventingtransmission of vibration generated by the gradient magnetic fieldgenerating part to other members via the closed vessel, the rigidstructure has a rigid reinforcing member provided on the sideconfronting the face on the imaging space side of the closed vessel, therigid structure has at least one connecting part connecting a face onthe imaging space side and a face confronting the face of the closedvessel inside the closed vessel, the rigid reinforcing member is fixedon the face confronting the face on the imaging space side of the closedvessel, and the rigid reinforcing member comprises at least one of aplate member and a grid member.
 2. The magnetic resonance imagingapparatus according to claim 1, wherein the plate member is integrallyformed with the closed vessel by making a wall thickness of the faceconfronting the face on the imaging space side of the closed vessellarger than the wall thickness of the face on the imaging space side. 3.The magnetic resonance imaging apparatus according to claim 1, whereineach closed vessel has a first recess provided for the face on theimaging space side, the connecting part comprises one or morethrough-holes provided inside so as to penetrate from the face on theimaging space side to the face confronting the foregoing face, eachgradient magnetic field generating part is fixed in the first recess,and in at least one of the through-holes, cables for gradient magneticfield for supplying a current to the gradient magnetic field generatingpart are disposed.
 4. The magnetic resonance imaging apparatus accordingto claim 3, wherein the through-holes are provided near the side face ofthe first recess.
 5. The magnetic resonance imaging apparatus accordingto claim 3, wherein at least one of the through-holes is provided at anapproximate center of the first recess.
 6. The magnetic resonanceimaging apparatus according to claim 3, wherein the rigid reinforcingmember is provided with one or more pathways communicating with thethrough-holes in the inside thereof, and the cables for gradientmagnetic field are disposed in one of the pathways.
 7. The magneticresonance imaging apparatus according to claim 6, which furthercomprises a means for circulating a refrigerant for cooling the gradientmagnetic field generating part, and wherein the gradient magnetic fieldgenerating part is provided with a means for passing the refrigerantinside, and piping for supplying the refrigerant to the gradientmagnetic field generating part is disposed in at least one of thethrough-holes and a pathway communicating therewith.
 8. The magneticresonance imaging apparatus according to claim 7, which furthercomprises a pair of high frequency magnetic field generating parts forgenerating a high frequency magnetic field in the imaging space, andwherein each of the pair of high frequency magnetic field generatingparts is disposed on the imaging space side with respect to the gradientmagnetic field generating part, and in at least one of the through-holesand a pathway communicating therewith, cables for high frequencymagnetic field for supplying a current to the high frequency magneticfield generating part are disposed.
 9. The magnetic resonance imagingapparatus according to claim 8, wherein three or more of thethrough-holes are provided in the closed vessel, and the cables forgradient magnetic field, the cables for high frequency magnetic fieldand the piping are disposed individually in the different through-holesand the different pathways communicating therewith.
 10. The magneticresonance imaging apparatus according to claim 9, wherein the differentpathways join inside the rigid reinforcing member to have a numbersmaller than the number of the through-holes, and communicate with theoutside of the rigid reinforcing member.
 11. The magnetic resonanceimaging apparatus according to claim 10, wherein a partition is providedin the joined pathways for separating a space through which the cablesfor gradient magnetic field or the cables for high frequency magneticfield pass and a space through which the piping passes in the pathway,and the partition is constituted with a material of high thermalconductivity.
 12. The magnetic resonance imaging apparatus according toclaim 11, wherein the piping is disposed at a position perpendicularlyunder the cables for gradient magnetic field or the cables for highfrequency magnetic field.
 13. The magnetic resonance imaging apparatusaccording to claim 7, wherein the through-hole has an opening inside thefirst recess, the gradient magnetic field generating part has arefrigerant receiving terminal at a position of the opening of thethrough-hole, the piping has a refrigerant supplying terminal, and therefrigerant receiving terminal is connected to the refrigerant supplyingterminal.
 14. The magnetic resonance imaging apparatus according toclaim 13, wherein the piping, the refrigerant supplying terminal and therefrigerant receiving terminal are constituted with a conductivematerial, so that they serve also as the cables for gradient magneticfield supplying an electric current to the gradient magnetic fieldgenerating part.
 15. The magnetic resonance imaging apparatus accordingto claim 3, wherein the through-bole has an opening inside the firstrecess, the gradient magnetic field generating pan has a currentreceiving terminal at a position of the opening of the through-hole, thecables for gradient magnetic field have a current supplying terminal,and the current supplying terminal is connected to the current receivingterminal.
 16. The magnetic resonance imaging apparatus according toclaim 3, wherein the cables for gradient magnetic field is fixed in thethrough-hole with a fixing member.
 17. The magnetic resonance imagingapparatus claim 1, wherein the closed vessel has a second recess in theface confronting the face on the imaging space side, and the rigidreinforcing member is disposed inside the second recess.
 18. Themagnetic resonance imaging apparatus according to claim 1, wherein theclosed vessel comprises one or more through-holes provided inside so asto penetrate from the face on the imaging space side to the faceconfronting the foregoing face, an opening of the grid member isprovided at a position corresponding to the through-holes.
 19. Themagnetic resonance imaging apparatus according to claim 1, wherein therigid reinforcing member has the plate member including a plurality ofseparate members.
 20. The magnetic resonance imaging apparatus accordingto claim 1, wherein each rigid reinforcing member of the closed vesselshas the same reinforcing structure.
 21. The A magnetic resonance imagingapparatus comprising a pair of static magnetic field generating sourcesopposingly disposed on both sides of an imaging space and a gradientmagnetic field generating part disposed on the imaging space side ofeach static magnetic field generating source for applying a gradientmagnetic field to the imaging space, wherein the static magnetic fieldgenerating sources each comprise a magnetic field generating coil and aclosed vessel enclosing the magnetic field generating coil inside, thegradient magnetic field generating part is supported on a face of theclosed vessel on the imaging space side, at least one of the closedvessel has a rigid structure for preventing transmission of vibrationgenerated by the gradient magnetic field generating part to othermembers via the closed vessel, the rigid structure has a rigidreinforcing member provided on the side confronting the face on theimaging space side of the closed vessel, the rigid reinforcing member isintegrally formed with the face confronting the face on the imagingspace side of the closed vessel, and the rigid reinforcing membercomprises at least one of a plate member and a grid member.
 22. Themagnetic resonance imaging apparatus according to claim 21, wherein theclosed vessel comprises one or more through-holes provided inside so asto penetrate front the face on the imaging space side to the faceconfronting the foregoing face, an opening of the grid member isprovided at a position corresponding to the through-holes.
 23. Themagnetic resonance imaging apparatus according to claim 21, wherein therigid reinforcing member has the plate member including a plurality ofseparate members.
 24. The magnetic resonance imaging apparatus accordingto claim 21, wherein the closed vessel comprises one or morethrough-holes provided inside so as to penetrate from the face on theimaging space side to the face confronting the foregoing face, the rigidreinforcing member has the plate member disposed only for a region ofdoughnut shape on the peripheral side from the through-holes.
 25. Themagnetic resonance imaging apparatus according to claim 21, wherein theplate member is integrally formed with the closed vessel by making awall thickness of the face confronting the face on the imaging spaceside of the closed vessel larger than the wall thickness of the face onthe imaging space side.
 26. A magnetic resonance imaging apparatuscomprising a pair of static magnetic field generating sources opposinglydisposed an both sides of an imaging space and a gradient magnetic fieldgenerating part disposed on the imaging space side of each staticmagnetic field generating source for applying a gradient magnetic fieldto the imaging space, wherein the static magnetic field generatingsources each comprise a magnetic field generating coil and a closedvessel enclosing the magnetic field generating coil inside, the gradientmagnetic field generating part is supported on a face of the closedvessel on the imaging space side, at least one of the closed vessel hasa rigid structure for preventing transmission of vibration generated bythe gradient magnetic field generating part to other members via theclosed vessel, the rigid structure has a rigid reinforcing memberprovided on the side confronting the face on the imaging space side ofthe closed vessel, and each rigid reinforcing member of the closedvessels has the different reinforcing structure.
 27. The magneticresonance imaging apparatus according to claim 26, wherein the rigidreinforcing member of upper closed vessel has the grid member, and therigid reinforcing member of lower closed vessels has the plate member.28. A magnetic resonance imaging apparatus comprising a pair of staticmagnetic field generating sources opposingly disposed on both sides ofan imaging space and a gradient magnetic field generating part disposedon the imaging space side of each static magnetic field generatingsource for applying a gradient magnetic field to the imaging space,wherein the static magnetic field generating sources each comprise amagnetic field generating coil and a closed vessel enclosing themagnetic field generating coil inside, the gradient magnetic fieldgenerating part is supported on a face of the closed vessel on theimaging space side, at least one of the closed vessel has a rigidstructure for preventing transmission of vibration generated by thegradient magnetic field generating part to other members via the closedvessel, the rigid structure has a rigid reinforcing member provided onthe side confronting the face on the imaging space side of the closedvessel, and the reinforcing members of each closed vessel has differentsizes or is made of different materials.